Geoffrey Canada, the man credited with turning around black under-achievement in Harlem and the star guest at conference, has told Michael Gove that the teaching unions are the biggest threat to the education secretary's reforms.

Canada has been hailed as a pioneer in education by Barack Obama. In an interview with the Guardian, Canada said he had told Gove that in the UK the unions constituted an inflexible brake which was "killing" the innovation necessary to transform children's lives, and that they "cover up" for failing teachers.

Canada said: "Our charter schools were not unionised. My contract with my teachers is fair, and is two pages. The union contract is 200 pages. You cannot manage your business when you cannot make any decision without going back to 200 pages worth of stuff.

"So that is inflexible. It kills innovation; it stops anything from changing. The only thing that we can do is what we did last year, and last year was another failure. So that to me makes no sense."

Canada's advice is a challenge to England's main teaching unions, which are opposed to coalition plans to expand academies and free schools, arguing they do not believe these schools raise standards, while costing more money to run and creating social segregation.

Asked what advice he had given Gove, Canada said: "I have been very clear that this union issue has to be at the forefront if you're going to bring about reform.

"It's uncomfortable and people get anxious about it. But I just think you have to have the conversation; and until we began to have that conversation in the States, there was no sense that you have any movement and momentum building towards reform.

"Until the unions come up with a real plan for improving schools that have failed – that doesn't do what they have done [in the past] – I think they don't have a really strong argument why they should be in this conversation in terms of what the future is going to be."

Canada grew up in a poor part of the New York Bronx, but went on to study at a prestigious liberal arts college and then specialise in education at Harvard.

He set up a not-for-profit organisation in Harlem where all the services a child and parent should get – from antenatal tips to skills training and after school services – are provided.

Called the Harlem Children's Zone, it has grown to cover 97 blocks. Obama has called for 20 similar "promise neighbourhoods" to do the same, across the US. Canada is now the subject of a film, Waiting for Superman, made by the director of An Inconvenient Truth.

The inability to sack bad teachers was a "real problem", and removing them from the profession should be made a priority, Canada said.

"Most teachers are decent, and some are really great. But there are also some who are lousy, and should not be in the profession. And the inability to get rid of these teachers, I think, is a real problem, and should be a priority, because it's pretty indefensible.

"Unions that cover up for people who we know should not be in the profession, that's a problem; when it is explicit that you may not get rid of these people."

Addressing the conference ahead of Gove's speech, Canada said he had earned unpopularity for calling attention to America's educational decline.

"I've been making sure everybody knows we have lost our way. We offer our children a third world education system. We are not in the top ten, and in many cases we are not even in the top 20. The fact is, we have mishandled the education system."

Where his project operates in New York, public schools have been failing for 53 years, he said.

"Fifty-three years?" he put it to conference. "All those generations. What has been the consequence of that failure? Has anyone changed anything? Even though it hasn't worked for 53 years?

"Education is the only billion dollar industry that tolerates abject failure. Any other business that failed so spectacularly for fifty years, it would be out of business."

Explaining his methods to conference, Canada said he tracked children from birth to college.

"You stop those kids at birth and you stay with those kids. You teach them the soft skills or learning, to shake off a disappointment, learning to concentrate. And you take responsibility.

"When we started our school, in Harlem, I said to our mayor … and I said to my board of trustees, I said – if I don't have a better school in five years than all the other private schools, I'm going to fire myself. And then I got my staff in and said 'but you all know I'll be the last one leaving'."